Variable-frequency sampling of battery voltage to determine fuel gauge power mode

ABSTRACT

A system for conserving power in an electronic device, in some embodiments, comprises: a battery to supply power to the electronic device; and a fuel gauge coupled to the battery and capable of operating in any of a plurality of power modes, wherein the fuel gauge selects its own power mode based on a repeated, variable-frequency sampling of a voltage provided by said battery.

BACKGROUND

Consumer electronics—such as smart phones, laptops, tablets, videocameras and handheld game consoles—are typically powered by batteries.Although such batteries are generally rechargeable, minimizing batteryconsumption has long been a primary design goal for such products.Extended battery life prolongs the amount of time between rechargingsessions, thus delivering a significantly enhanced user experience.

SUMMARY

At least some of the embodiments disclosed herein are directed to asystem for conserving power in an electronic device, comprising: abattery to supply power to the electronic device; and a fuel gaugecoupled to the battery and capable of operating in any of a plurality ofpower modes, wherein the fuel gauge selects its own power mode based ona repeated, variable-frequency sampling of a voltage provided by saidbattery. At least some of these embodiments may be supplemented usingone or more of the following concepts, in any order or combination:wherein the fuel gauge repeatedly samples said voltage at a samplingfrequency corresponding to a currently-enabled power mode of the fuelgauge; wherein the power mode is selected from at least two differentpower modes, and wherein a higher one of said at least two differentpower modes is associated with more frequent sampling of said voltage bythe fuel gauge, and wherein a lower one of said at least two differentpower modes is associated with less frequent sampling of said voltage bythe fuel gauge; wherein said power mode is selected from the groupconsisting of: a stand by mode, a relax mode, an operation mode and anactive mode; wherein the fuel gauge switches to a higher power mode thanits currently-enabled power mode if said repeated sampling demonstratesa change in said voltage that meets or exceeds a voltage changethreshold; wherein the fuel gauge maintains its currently-enabled powermode if said repeated sampling demonstrates a change in said voltagethat fails to meet or exceed a voltage change threshold; wherein thefuel gauge switches to a lower power mode than its currently-enabledpower mode if said repeated sampling demonstrates no change in saidvoltage; wherein the electronic device is selected from the groupconsisting of: a smart phone, a tablet, a laptop, a digital camera, anda handheld game console; wherein the fuel gauge selects its power modebased on four consecutive samples of said voltage.

At least some embodiments are directed to an electronic device,comprising: a battery that powers at least part of the electronicdevice; and a fuel gauge, coupled to the battery, that autonomouslyselects a power mode in which to operate based on a sampling of avoltage provided by said battery, wherein the fuel gauge selects saidpower mode based on a degree to which said voltage swings betweensamples and based on how often said voltage changes. At least some ofthese embodiments may be supplemented with one or more of the followingconcepts, in any order and in any combination: wherein, while operatingwithin a single fuel gauge power mode, the fuel gauge varies a samplingfrequency at which the fuel gauge samples said voltage; furthercomprising a programmable register that stores a voltage changethreshold against which the fuel gauge compares said degree to which thevoltage swings between samples and that stores a rate of changethreshold against which the fuel gauge compares how often said voltagechanges, and wherein the fuel gauge uses said comparisons to select saidpower mode; wherein a sampling frequency at which the fuel gauge samplessaid voltage is based on a currently-enabled power mode of the fuelgauge; wherein, if the fuel gauge determines that said voltage does notchange over a predetermined number of consecutive samples, the fuelgauge switches to a lower power mode than its currently-enabled powermode; wherein, if the greatest battery voltage swing over apredetermined number of consecutive voltage samples is less than avoltage change threshold, or if the number of times that the batteryvoltage changes over said predetermined number of consecutive voltagesamples is less than a rate of change threshold, the fuel gaugemaintains its currently-enabled power mode; wherein, if the greatestbattery voltage swing over a predetermined number of consecutive voltagesamples is equal to or greater than a voltage change threshold, and ifthe number of times that the battery voltage changes over saidpredetermined number of consecutive voltage samples is equal to orgreater than a rate of change threshold, the fuel gauge switches to ahigher power mode than its currently-enabled power mode.

At least some embodiments are directed to a method for conserving power,comprising: repeatedly sampling a voltage provided by a battery housedwithin an electronic device; and selecting a fuel gauge power mode basedon said repeated sampling, wherein said repeated sampling is performedat a variable sampling frequency that depends on a currently-enabledpower mode of the fuel gauge, wherein said selecting is performed by thefuel gauge. At least some of these embodiments may be supplemented byone or more of the following concepts, in any order and in anycombination: wherein said fuel gauge power mode is selected from thegroup consisting of: a standby mode, a relaxed mode, an operation mode,and an active mode; wherein the fuel gauge samples said voltage at afirst sampling frequency during the relaxed mode, at a second samplingfrequency during the operation mode, and at a third sampling frequencyduring the active mode, and wherein the second sampling frequency isgreater than the first sampling frequency but less than the thirdsampling frequency; further comprising varying the sampling frequencywhile operating within a single fuel gauge power mode.

BRIEF DESCRIPTION OF THE DRAWINGS

There are disclosed in the drawings and in the following descriptionsystems and methods for variable-frequency sampling of an electronicdevice battery voltage to determine a fuel gauge power mode. In thedrawings:

FIG. 1 is a front view of an illustrative electronic device.

FIG. 2 is a block diagram of at least some components within anelectronic device.

FIG. 3 is a block diagram of at least some components within a fuelgauge of the electronic device.

FIG. 4 is a graph illustrating a variable frequency voltage samplingscheme.

FIG. 5 is a flow diagram of an illustrative method usable to implementthe techniques disclosed herein.

It should be understood, however, that the specific embodiments given inthe drawings and detailed description thereto do not limit thedisclosure. On the contrary, they provide the foundation for one ofordinary skill to discern the alternative forms, equivalents, andmodifications that are encompassed together with one or more of thegiven embodiments in the scope of the appended claims.

DETAILED DESCRIPTION

Disclosed herein are methods and systems for variable-frequency samplingof an electronic device battery voltage to determine a fuel gauge powermode. An illustrative electronic device implementing the techniquesdisclosed herein contains a battery supplying power to the components ofthe electronic device and a fuel gauge that monitors the battery. Thefuel gauge is capable of operating in numerous power modes (e.g.,standby mode, relaxed mode, operating mode, active mode), each one ofwhich causes the fuel gauge to consume different amounts of power. Thefuel gauge selects its power mode based on a sampling of the voltageprovided by the battery. The fuel gauge samples this voltage at avariable frequency, with the precise frequency depending on the powermode in which the fuel gauge is currently operating and changing as thefuel gauge power mode changes. Based on the voltage swings betweensamples and on how often the voltage changes, the fuel gauge eitherswitches to a lower power mode, stays in its currently-enabled powermode, or switches to a higher power mode.

For example, while the fuel gauge is in a standby mode, it may samplethe battery voltage once per minute; in a relaxed mode, once every 20seconds; in an operating mode, once every 10 seconds; and in an activemode, four times per second. If, while in any of these power modes, thefuel gauge consecutively samples the battery voltage a predeterminednumber of times and determines that there is no voltage change, the fuelgauge autonomously switches to a lower power mode (unless the fuel gaugeis already in the lowest available power mode, such as a standby mode).If the fuel gauge consecutively samples the battery voltage thepredetermined number of times and determines that there is at least onevoltage change but that the greatest voltage change (in eitherdirection) fails to meet or exceed a voltage change threshold, the fuelgauge remains in its currently-enabled power mode. Similarly, if thefuel gauge consecutively samples the battery voltage the predeterminednumber of times and determines that there is a threshold-exceedingvoltage change but that the battery voltage does not change often enoughto meet or exceed a rate of change threshold, the fuel gauge remains inits currently-enabled power mode. Finally, if the fuel gauge determinesthat there is at least one voltage change and that the greatest of thesevoltage changes meets or exceeds the voltage change threshold, andfurther if the fuel gauge determines that the battery voltage changesoften enough to meet or exceed a rate of change threshold, the fuelgauge switches to a higher power mode (unless the fuel gauge is alreadyin the highest available power mode, such as an active mode). Numerousvariations and permutations of this technique are contemplated andincluded within the scope of the disclosure.

In some embodiments, the sampling frequency may vary even within thesame fuel gauge power mode. For example, referring again to theforegoing example, if the fuel gauge determines that there is anincrease in voltage variation (i.e., greater voltage swings betweensamples and/or a greater percentage of samples indicating voltagechanges), but the voltage variation is not significant enough to warrantswitching modes, the fuel gauge may remain in its currently-enabledpower mode but it may increase or decrease its sampling frequency toaccount for the increased variation in battery voltage.

FIG. 1 is a front view of an illustrative consumer electronic device 100that implements the systems and methods described herein. The electronicdevice 100 may be any suitable device that uses a battery (e.g., alithium ion battery). Non-limiting examples of such electronic devicesinclude smart phones (e.g., APPLE iPHONE®, SAMSUNG GALAXY NOTE®),tablets (e.g., APPLE iPAD®, AMAZON KINDLE®), laptops, video cameras(including camcorders), and handheld game consoles (e.g., SONYPLAYSTATION VITA®). Other such devices are contemplated and includedwithin the scope of this disclosure. The illustrative consumerelectronic device 100 includes a display screen 102 that is preferably atouch screen. It further includes various tactile input devices 104,such as buttons arranged in various locations around the exterior of theelectronic device 100. Additional input and output devices, such asmicrophones and speakers, also may be incorporated within such a device.

FIG. 2 is a block diagram of components within the illustrative consumerelectronic device 100. The electronic device 100 includes anapplication-specific integrated circuit (ASIC) 200 comprising processinglogic 202 (e.g., a microprocessor), storage 206 coupled to theprocessing logic 202 and comprising software code 204 (e.g., anoperating system or applications), input features 208 (e.g., buttons,touch screen, microphone), output features 210 (e.g., display screenthat may be the same as the touch screen, speaker, haptic feedbackmotor), and a network interface 212 for communicating with other devices(e.g., via the Internet). Other components may be included on the ASIC200. The ASIC 200 is powered by a battery pack (“battery”) 214. A fuelgauge 216 couples to the battery 214. In at least some embodiments, theASIC 200, the fuel gauge 216 and the battery 214 couple to each other ina parallel configuration, so that the ASIC 200 may receive power fromthe battery 214 while the fuel gauge 216 monitors the output of thebattery 214. Further, in some embodiments the ASIC 200 may be replacedby a plurality of ASICs or other circuitry. The techniques disclosedherein may be implemented in any electronic device in which any suitabletype of load (here, the ASIC 200) is powered by the battery 214. Inoperation, and as described in greater detail with respect to FIG. 3,the fuel gauge 216 monitors the voltage output by the battery 214. Asexplained above, the fuel gauge 216 autonomously selects its own powermode based on the battery voltage fluctuation—that is, based on thebattery voltage swings between samples as well as the frequency withwhich the battery voltage changes.

FIG. 3 is a block diagram of components within the consumer electronicdevice 100 and, more particularly, within the fuel gauge 216. The blockdiagram of FIG. 3 is conceptual in nature, meaning that at least some ofthe blocks represent functions performed by the various parts of theelectronic device 100. The actual circuit logic used to implement thefunctions represented by the blocks may vary depending on designconsiderations and preferences and will be readily known to ordetermined by one of ordinary skill in the art.

Referring to FIG. 3, the battery 214 contains a voltage source 300 thatcreates a potential across terminals 302, 304. The terminal 302 providesa voltage to node 318, which couples to the fuel gauge 216 and to theASIC 200. The terminal 304 couples to ground and to node 320, whichcouples to the fuel gauge 216 and the ASIC 200. The fuel gauge 216comprises voltage detection logic 306, a programmable voltagefluctuation level register 308, mode control logic 310, a clock 312 andport 314, and a sampling timer 316. The programmable register 308contains the voltage change threshold value and the rate of changethreshold value, described above. In operation, the voltage detectionlogic 306 samples the voltage present at node 318 (i.e., the batteryvoltage) at a sampling frequency that varies according to thecurrently-enabled mode of the fuel gauge 216. In at least someembodiments, when the fuel gauge 216 is in a standby mode, the voltagedetection logic 306 may sample the battery voltage once per minute; in arelaxed mode, once every 20 seconds; in an operating mode, once every 10seconds; and in an active mode, four times per second, although thescope of disclosure is not limited to these sampling frequencies foreach power mode, nor is the scope of disclosure limited to the use of asingle sampling frequency in individual power modes.

If, upon consecutively sampling the voltage a predetermined number oftimes, the logic 306 determines that the voltage has not changed at all,the fuel gauge 216 switches to a lower power mode. If the logic 306determines that the voltage has changed, but not by the voltage changethreshold stored in the register 308, or if the logic 306 determinesthat the voltage has changed by the voltage change threshold but thatthe voltage has not changed as often as required by the rate of changethreshold, the logic 306 concludes that there is not enough variation inthe battery voltage to warrant an upward power mode switch, and itremains in its currently-enabled power mode. If, however, the logic 306determines that the battery voltage has changed by the voltage changethreshold, and if the logic 306 further determines that the voltage haschanged often enough (by any suitable amount, or by some additionalminimum threshold programmed into the register 308) to meet or exceedthe rate of change threshold, the logic 306 issues a signal to the modecontrol logic 310 to increase the power mode of the fuel gauge 216.

FIG. 4 is a graph 400 illustrating a variable frequency voltage samplingscheme. The graph 400 plots different power modes on the x-axis 402 andpower level on the y-axis 404. Specifically, graph 400 shows a standbymode 406, a relaxed mode 408, an operation mode 410, and an active mode412. During the standby mode 406, the power level 414 is relatively low;during the relaxed mode 408, the power level 416 is increased; duringthe operation mode 410, the power level 418 is further increased; andduring the active mode 412, the power level 420 is highest. The samplingfrequency at which the fuel gauge samples the battery voltage variesamong these power modes. During standby mode 406, numeral 422 indicatesa relatively low sampling frequency; during relaxed mode 408, numeral424 indicates an increased sampling frequency; during the operation mode410, the sampling frequency 426 is further increased; and during theactive mode 412, the sampling frequency 428 is relatively high.Specific, illustrative sampling frequencies are provided above and thusare not reproduced here.

FIG. 5 is a flow diagram of an illustrative method 500 usable toimplement the techniques disclosed herein. The method 500 begins bydetermining a current fuel gauge power mode (step 502). The method 500includes performing a sampling operation in the current power mode (step504). A sampling operation is a sampling of the battery voltage apredetermined number of times at a predetermined sampling frequency,where the sampling frequency is determined based at least on the currentpower mode of the fuel gauge. The method 500 then includes determiningwhether the results of the sampling operation met the criteria forincreasing the fuel gauge power mode (step 506). If so, the fuel gaugeautonomously increases its power mode (step 508). Otherwise, the method500 comprises determining whether the results of the sampling operationmet the criteria for decreasing the fuel gauge power mode (step 510). Ifso, the fuel gauge autonomously decreases its power mode (step 512).Otherwise, the currently-enabled power mode is maintained. Control ofthe method 500 then returns to step 504, as is the case after completionof steps 508 and 512. The method 500 may be modified as desired—forexample, to include additional steps, delete steps, or rearrange steps.

Numerous other variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations, modifications and equivalents. In addition, the term“or” should be interpreted in an inclusive sense.

What is claimed is:
 1. A system for conserving power in an electronicdevice, comprising: a battery to supply power to the electronic device;and a fuel gauge coupled to the battery and capable of operating in anyof a plurality of power modes, wherein the fuel gauge selects its ownpower mode based on a repeated, variable-frequency sampling of a voltageprovided by said battery.
 2. The system of claim 1, wherein the fuelgauge repeatedly samples said voltage at a sampling frequencycorresponding to a currently-enabled power mode of the fuel gauge. 3.The system of claim 2, wherein the power mode is selected from at leasttwo different power modes, and wherein a higher one of said at least twodifferent power modes is associated with more frequent sampling of saidvoltage by the fuel gauge, and wherein a lower one of said at least twodifferent power modes is associated with less frequent sampling of saidvoltage by the fuel gauge.
 4. The system of claim 1, wherein said powermode is selected from the group consisting of: a stand by mode, a relaxmode, an operation mode and an active mode.
 5. The system of claim 1,wherein the fuel gauge switches to a higher power mode than itscurrently-enabled power mode if said repeated sampling demonstrates achange in said voltage that meets or exceeds a voltage change threshold.6. The system of claim 1, wherein the fuel gauge maintains itscurrently-enabled power mode if said repeated sampling demonstrates achange in said voltage that fails to meet or exceed a voltage changethreshold.
 7. The system of claim 1, wherein the fuel gauge switches toa lower power mode than its currently-enabled power mode if saidrepeated sampling demonstrates no change in said voltage.
 8. The systemof claim 1, wherein the electronic device is selected from the groupconsisting of: a smart phone, a tablet, a laptop, a digital camera, anda handheld game console.
 9. The system of claim 1, wherein the fuelgauge selects its power mode based on four consecutive samples of saidvoltage.
 10. An electronic device, comprising: a battery that powers atleast part of the electronic device; and a fuel gauge, coupled to thebattery, that autonomously selects a power mode in which to operatebased on a sampling of a voltage provided by said battery, wherein thefuel gauge selects said power mode based on a degree to which saidvoltage swings between samples and based on how often said voltagechanges.
 11. The electronic device of claim 10, wherein, while operatingwithin a single fuel gauge power mode, the fuel gauge varies a samplingfrequency at which the fuel gauge samples said voltage.
 12. Theelectronic device of claim 10, further comprising a programmableregister that stores a voltage change threshold against which the fuelgauge compares said degree to which the voltage swings between samplesand that stores a rate of change threshold against which the fuel gaugecompares how often said voltage changes, and wherein the fuel gauge usessaid comparisons to select said power mode.
 13. The electronic device ofclaim 10, wherein a sampling frequency at which the fuel gauge samplessaid voltage is based on a currently-enabled power mode of the fuelgauge.
 14. The electronic device of claim 10, wherein, if the fuel gaugedetermines that said voltage does not change over a predetermined numberof consecutive samples, the fuel gauge switches to a lower power modethan its currently-enabled power mode.
 15. The electronic device ofclaim 10, wherein, if the greatest battery voltage swing over apredetermined number of consecutive voltage samples is less than avoltage change threshold, or if the number of times that the batteryvoltage changes over said predetermined number of consecutive voltagesamples is less than a rate of change threshold, the fuel gaugemaintains its currently-enabled power mode.
 16. The electronic device ofclaim 10, wherein, if the greatest battery voltage swing over apredetermined number of consecutive voltage samples is equal to orgreater than a voltage change threshold, and if the number of times thatthe battery voltage changes over said predetermined number ofconsecutive voltage samples is equal to or greater than a rate of changethreshold, the fuel gauge switches to a higher power mode than itscurrently-enabled power mode.
 17. A method for conserving power,comprising: repeatedly sampling a voltage provided by a battery housedwithin an electronic device; and selecting a fuel gauge power mode basedon said repeated sampling, wherein said repeated sampling is performedat a variable sampling frequency that depends on a currently-enabledpower mode of the fuel gauge, wherein said selecting is performed by thefuel gauge.
 18. The method of claim 17, wherein said fuel gauge powermode is selected from the group consisting of: a standby mode, a relaxedmode, an operation mode, and an active mode.
 19. The method of claim 18,wherein the fuel gauge samples said voltage at a first samplingfrequency during the relaxed mode, at a second sampling frequency duringthe operation mode, and at a third sampling frequency during the activemode, and wherein the second sampling frequency is greater than thefirst sampling frequency but less than the third sampling frequency. 20.The method of claim 17, further comprising varying the samplingfrequency while operating within a single fuel gauge power mode.